The benefits and drawbacks of HITT (Intervals) and steady state cardio
For decades bodybuilders have used low intensity cardio training during their dieting phase to get in shape for contests. Without access to some of the advances in training, nutrition, and supplements in recent years, these bodybuilders consistently got in great shape time after time with a low level of body fat and a very small waist seen among many athletes from that era. Why then has there been a trend for steady state, low intensity cardio to be dismissed as a short cut to getting fat and dropping muscle?
In the fitness community we encounter a lot of trends, with certain things becoming fashionable for a time before someone rails against it, leading to an inevitable backlash against what was formerly very popular. Think of the number of different fitness crazes that last for a couple of years before sinking into obscurity. This no doubt explains why many gyms feel the need to change their equipment types all the time and constantly introduce new gimmicks.
Today, high intensity interval training (HIIT) is often proclaimed to be superior to steady state cardio in every way. Proponents argue that HIIT leads to greater fat loss and less muscle tissue loss than regular cardio. To determine the extent to which this is true we must first define the two forms of training then take a look at the benefits and costs associated with each.
Defining steady state cardio and HIIT
As the name suggests, steady state cardio involves maintaining a low to medium intensity of effort for a prolonged duration. Many people performing this type of training have tended to focus on getting their heart rates up to a supposed ‘fat burning zone’. As we will discover, the notion of a particular fat burning zone is based in a false reading of the research. However, this notion has been promulgated for so long that many people now accept it as fact.
Generally speaking, steady state cardio involves keeping the heart rate in the range of 100-150bpm, typically for periods of 20-60 minutes.
On the other hand, HIIT (high intensity interval training) involves intermittent high-intensity activity interspersed with periods of zero to low activity and repeated for a number of sets/intervals.
Technically, the phrase ‘interval training’ applies to activities such as weight training and to the type of workout performed by many competitive 100m sprinters. The main things that distinguish interval training are the emphasis on incomplete recovery and the goal of improving performance, whereas HIIT is used specifically to improve body composition.
A typical HIIT workout will involve 10-60 second bursts of high intensity activity employing a variety of modalities such as running, cycling, rowing and stair climbing. These are interspersed with rest periods of anywhere between 10 and 240 seconds. Typically a work:rest ratio of 1:1-1.5 is employed.
Now that we are on the same page regarding what constitutes steady state cardio versus HIIT, it is time to consider the relative costs and benefits associated with each as well as some of the arguments that can be made in support of both types of training.
Steady State Cardio Benefits
Less taxing. On the face of it, steady state cardio is a lot easier to perform, making it a better choice for people who are unfit or already perform a lot of high intensity activity. The former group would be unable to train at a sufficiently high intensity to get anything out of intervals in the first place. For the latter group, athletes performing heavy leg sessions may find that including intervals in their training could impede their recovery as well as being more neurally taxing than steady state cardio.
Burns more calories. Although interval sessions burn more calories per unit of time, the ability to perform cardio for longer time periods means that more total calories can be burned during steady state cardio.
Frequency. It is easier to recover after performing lower-intensity exercise so cardio can be performed more frequently than intervals, and potentially on a daily basis.
Steady State Cardio Drawbacks
Muscle loss. There is little doubt that performing a lot of endurance work leads to metabolic adaptations that bias the body to burning off muscle tissue. For evolutionary reasons, it makes sense to trim muscle mass if seeking great endurance levels. Related to the loss in muscle mass is the promotion of slow twitch muscle fibres and accelerated loss of fast twitch muscle fibres. For an athlete involved in a sport requiring high levels of strength or speed this is a big issue.
Boring. Long sessions on the bike or rowing machine can be anathema to anaerobic athletes used to lifting using high intensity techniques. Although a lot of endurance buffs enjoy their runs it seems to be the case that cardio is only enjoyable for those who naturally gravitate towards it. This is an issue if a strength athlete fails to perform his cardio due to boredom.
Chronic injuries. Pounding the pavement is associated with a higher degree of joint injuries. To a certain extent, overuse injuries will occur during any physical activity including in the weight room and the way to help avoid them is to rotate your exercises and cardio choices.
Interval Training (HIIT) Benefits
Time efficient. Intervals can be completed in as little as ten minutes or less making them a very time efficient form of training.
High intensity. The fact that HIIT means performing at maximal effort makes it somewhat more similar to weight training than cardio, a feature that makes it more attractive to most strength athletes who like a challenge but get bored easily.
Metabolic similarities. Because HIIT tends to utilise similar exercise intensities and durations as regular weight training, it’s easier to implement for athletes who want to match the motor qualities of their cardio with what they do in the gym. Nutritionally speaking, both HIIT and weight training will respond favourably to supplements such as creatine and beta alanine, for instance.
Enhances fat burning. Compared to regular cardio, intervals are associated with enhanced utilisation of fat as a fuel store.
Increased EPOC. EPOC means excess post exercise oxygen consumption. In layman's terms, it means the number of calories you burn after your exercise session is completed. Intervals burn more calories after working out than does regular cardio.
Enhanced production of fat burning hormones. Compared to normal cardio, HIIT leads to greater release of endogenous fat burning hormones such as adrenaline and noradrenaline, which are associated with greater thermogenesis. In addition, the action of these compounds can lead to the suppression of appetite commonly seen with high intensity activity.
Interval Training (HIIT) Drawbacks
Unsuitable for some. Intervals are unlikely to be a good fit for those who are either not very fit or not used to working hard in the gym, as such individuals will be unable or unwilling to push themselves to the degree needed to make this form of training work for them.
Fewer calories burned. As noted, the average interval session burns fewer calories than a cardio session, which can be performed both for longer and more frequently.
Recovery issues. When it comes to leg activity, it is difficult to perform intervals at a suitable intensity to elicit fat loss effects whilst avoiding overtraining. Those who attempt to do high intensity leg work can often end up feeling sore all week long.
Acute injuries. Whilst enormous amounts of steady state cardio can cause overuse injuries, the intensity of intervals can easily lead to acute injuries such as hamstring pulls or sprains and muscle tears. For heavier people in particular, the stresses imposed on joints by performing sprints correlates with a heightened risk of injury.
Low frequency. As stated previously, intervals cannot be performed more than two to three times a week at the very most, maybe less if you are working your legs hard in the gym. Intervals are therefore not ideal for people who want to train daily as part of their routine (e.g. those who find that this helps them stick to their plan).
Pain. Make no mistake, provided intervals are performed properly they hurt and some people are quite simply unable to tolerate the pain needed to obtain results using this method.
Still not sure which form of training would be best for you? Check out Part 2 for more information on interval training’s EPOC and discover whether or not this makes it superior to steady state cardio.